﻿using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Runtime.InteropServices;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting.Channels.Ipc;
using System.Runtime.Serialization.Formatters;
using System.Security;
using System.Text;
using System.Threading;
using System.Windows;
using System.Windows.Threading;

namespace DeltaEngine.Editor.Helpers
{
	/// <summary>
	/// Checks to make sure that only one instance of this application is running at a time.
	/// </summary>
	public static class SingleInstance<TApplication>
		where TApplication : Application, SingleInstanceApp
	{
		private const string Delimiter = ":";
		private const string ChannelNameSuffix = "SingeInstanceIPCChannel";
		private const string RemoteServiceName = "SingleInstanceApplicationService";
		private const string IpcProtocol = "ipc://";

		// ReSharper disable StaticFieldInGenericType
		private static Mutex singleInstanceMutex;
		private static IpcServerChannel channel;
		private static IList<string> commandLineArgs;
		public static IList<string> CommandLineArgs
		{
			get { return commandLineArgs; }
		}

		/// <summary>
		/// Checks if the instance of the application attempting to start is the first instance. 
		/// If not, activates the first instance.
		/// </summary>
		public static bool InitializeAsFirstInstance(string uniqueName)
		{
			commandLineArgs = GetCommandLineArgs(uniqueName);
			string applicationIdentifier = uniqueName + Environment.UserName;
			string channelName = String.Concat(applicationIdentifier, Delimiter, ChannelNameSuffix);
			bool firstInstance;
			singleInstanceMutex = new Mutex(true, applicationIdentifier, out firstInstance);
			if (firstInstance)
				CreateRemoteService(channelName);
			else
				SignalFirstInstance(channelName, commandLineArgs);
			return firstInstance;
		}

		/// <summary>
		/// Cleans up single-instance code, clearing shared resources, mutexes, etc.
		/// </summary>
		public static void Cleanup()
		{
			if (singleInstanceMutex != null)
			{
				singleInstanceMutex.Close();
				singleInstanceMutex = null;
			}
			if (channel != null)
			{
				ChannelServices.UnregisterChannel(channel);
				channel = null;
			}
		}

		/// <summary>
		/// Gets command line args - for ClickOnce deployed applications, command line args may not be
		/// passed directly, they have to be retrieved.
		/// </summary>
		private static IList<string> GetCommandLineArgs(string uniqueApplicationName)
		{
			string[] args = null;
			if (AppDomain.CurrentDomain.ActivationContext == null)
				// The application was not clickonce deployed, get args from standard API
				args = Environment.GetCommandLineArgs();
			else
			{             
				string appFolderPath =
					Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
						uniqueApplicationName);
				string cmdLinePath = Path.Combine(appFolderPath, "cmdline.txt");
				if (File.Exists(cmdLinePath))
					try
					{
						args = TryGetCommandLineArgs(cmdLinePath);
					}
					catch (IOException) {}
			}
			if (args == null)
				args = new string[] { };
			return new List<string>(args);
		}

		private static string[] TryGetCommandLineArgs(string cmdLinePath)
		{
			string[] args;
			using (TextReader reader = new StreamReader(cmdLinePath, Encoding.Unicode))
			args = NativeMethods.CommandLineToArgvW(reader.ReadToEnd());
			File.Delete(cmdLinePath);
			return args;
		}

		private static void CreateRemoteService(string channelName)
		{
			var serverProvider = new BinaryServerFormatterSinkProvider();
			serverProvider.TypeFilterLevel = TypeFilterLevel.Full;
			IDictionary props = new Dictionary<string, string>();
			props["name"] = channelName;
			props["portName"] = channelName;
			props["exclusiveAddressUse"] = "false";
			// Create the IPC Server channel with the channel properties
			channel = new IpcServerChannel(props, serverProvider);
			// Register the channel with the channel services
			ChannelServices.RegisterChannel(channel, true);
			// Expose the remote service with the REMOTE_SERVICE_NAME
			var remoteService = new IPCRemoteService();
			RemotingServices.Marshal(remoteService, RemoteServiceName);
		}

		/// <summary>
		/// Creates a client channel and obtains a reference to the remoting service exposed by the server.
		/// The remoting service exposed by the first instance. Calls a function of the remoting service 
		/// class to pass on command line arguments from the second instance to the first and activate it.
		/// </summary>
		private static void SignalFirstInstance(string channelName, IList<string> args)
		{
			var secondInstanceChannel = new IpcClientChannel();
			ChannelServices.RegisterChannel(secondInstanceChannel, true);
			string remotingServiceUrl = IpcProtocol + channelName + "/" + RemoteServiceName;
			var firstInstanceRemoteServiceReference =
				(IPCRemoteService)RemotingServices.Connect(typeof(IPCRemoteService), remotingServiceUrl);
			if (firstInstanceRemoteServiceReference != null)
				firstInstanceRemoteServiceReference.InvokeFirstInstance(args);
		}

		private static object ActivateFirstInstanceCallback(object argument)
		{
			var args = argument as IList<string>;
			ActivateFirstInstance(args);
			return null;
		}

		/// <summary>
		/// Activates the first instance of the application with arguments from a second instance.
		/// </summary>
		private static void ActivateFirstInstance(IList<string> args)
		{
			if (Application.Current != null)
				((TApplication)Application.Current).SignalExternalCommandLineArguments(args);
		}

		/// <summary>
		/// Remoting service class which is exposed by the server i.e the first instance and called by the
		/// second instance to pass on the command line arguments to the first instance and activate itself.
		/// </summary>
		private class IPCRemoteService : MarshalByRefObject
		{
			public void InvokeFirstInstance(IList<string> args)
			{
				if (Application.Current != null)
					Application.Current.Dispatcher.BeginInvoke(DispatcherPriority.Normal,
						new DispatcherOperationCallback(ActivateFirstInstanceCallback), args);
			}

			/// <summary>
			/// Remoting Object's ease expires after every 5 minutes by default. We need to override the
			/// InitializeLifetimeService class to ensure that lease never expires.
			/// </summary>
			public override object InitializeLifetimeService()
			{
				return null;
			}
		}
	}


	[SuppressUnmanagedCodeSecurity]
	internal static class NativeMethods
	{
		public delegate IntPtr MessageHandler(WM uMsg, IntPtr wParam, IntPtr lParam, out bool handled);

		[DllImport("shell32.dll", EntryPoint = "CommandLineToArgvW", CharSet = CharSet.Unicode)]
		private static extern IntPtr _CommandLineToArgvW(
			[MarshalAs(UnmanagedType.LPWStr)] string cmdLine, out int numArgs);

		[DllImport("kernel32.dll", EntryPoint = "LocalFree", SetLastError = true)]
		private static extern IntPtr _LocalFree(IntPtr hMem);

		public static string[] CommandLineToArgvW(string cmdLine)
		{
			IntPtr argumentPointer = IntPtr.Zero;
			try
			{
				int numArgs;
				argumentPointer = _CommandLineToArgvW(cmdLine, out numArgs);
				if (argumentPointer == IntPtr.Zero)
					throw new Win32Exception();
				var result = new string[numArgs];
				for (int i = 0; i < numArgs; i++)
				{
					IntPtr currentArgument = Marshal.ReadIntPtr(argumentPointer, i * Marshal.SizeOf(typeof(IntPtr)));
					result[i] = Marshal.PtrToStringUni(currentArgument);
				}
				return result;
			}
			finally
			{
				_LocalFree(argumentPointer);
			}
		}
	}

	internal enum WM
	{
		// ReSharper disable InconsistentNaming
		// ReSharper disable IdentifierTypo
		NULL = 0x0000,
		CREATE = 0x0001,
		DESTROY = 0x0002,
		MOVE = 0x0003,
		SIZE = 0x0005,
		ACTIVATE = 0x0006,
		SETFOCUS = 0x0007,
		KILLFOCUS = 0x0008,
		ENABLE = 0x000A,
		SETREDRAW = 0x000B,
		SETTEXT = 0x000C,
		GETTEXT = 0x000D,
		GETTEXTLENGTH = 0x000E,
		PAINT = 0x000F,
		CLOSE = 0x0010,
		QUERYENDSESSION = 0x0011,
		QUIT = 0x0012,
		QUERYOPEN = 0x0013,
		ERASEBKGND = 0x0014,
		SYSCOLORCHANGE = 0x0015,
		SHOWWINDOW = 0x0018,
		ACTIVATEAPP = 0x001C,
		SETCURSOR = 0x0020,
		MOUSEACTIVATE = 0x0021,
		CHILDACTIVATE = 0x0022,
		QUEUESYNC = 0x0023,
		GETMINMAXINFO = 0x0024,
		WINDOWPOSCHANGING = 0x0046,
		WINDOWPOSCHANGED = 0x0047,
		CONTEXTMENU = 0x007B,
		STYLECHANGING = 0x007C,
		STYLECHANGED = 0x007D,
		DISPLAYCHANGE = 0x007E,
		GETICON = 0x007F,
		SETICON = 0x0080,
		NCCREATE = 0x0081,
		NCDESTROY = 0x0082,
		NCCALCSIZE = 0x0083,
		NCHITTEST = 0x0084,
		NCPAINT = 0x0085,
		NCACTIVATE = 0x0086,
		GETDLGCODE = 0x0087,
		SYNCPAINT = 0x0088,
		NCMOUSEMOVE = 0x00A0,
		NCLBUTTONDOWN = 0x00A1,
		NCLBUTTONUP = 0x00A2,
		NCLBUTTONDBLCLK = 0x00A3,
		NCRBUTTONDOWN = 0x00A4,
		NCRBUTTONUP = 0x00A5,
		NCRBUTTONDBLCLK = 0x00A6,
		NCMBUTTONDOWN = 0x00A7,
		NCMBUTTONUP = 0x00A8,
		NCMBUTTONDBLCLK = 0x00A9,
		SYSKEYDOWN = 0x0104,
		SYSKEYUP = 0x0105,
		SYSCHAR = 0x0106,
		SYSDEADCHAR = 0x0107,
		COMMAND = 0x0111,
		SYSCOMMAND = 0x0112,
		MOUSEMOVE = 0x0200,
		LBUTTONDOWN = 0x0201,
		LBUTTONUP = 0x0202,
		LBUTTONDBLCLK = 0x0203,
		RBUTTONDOWN = 0x0204,
		RBUTTONUP = 0x0205,
		RBUTTONDBLCLK = 0x0206,
		MBUTTONDOWN = 0x0207,
		MBUTTONUP = 0x0208,
		MBUTTONDBLCLK = 0x0209,
		MOUSEWHEEL = 0x020A,
		XBUTTONDOWN = 0x020B,
		XBUTTONUP = 0x020C,
		XBUTTONDBLCLK = 0x020D,
		MOUSEHWHEEL = 0x020E,
		CAPTURECHANGED = 0x0215,
		ENTERSIZEMOVE = 0x0231,
		EXITSIZEMOVE = 0x0232,
		IME_SETCONTEXT = 0x0281,
		IME_NOTIFY = 0x0282,
		IME_CONTROL = 0x0283,
		IME_COMPOSITIONFULL = 0x0284,
		IME_SELECT = 0x0285,
		IME_CHAR = 0x0286,
		IME_REQUEST = 0x0288,
		IME_KEYDOWN = 0x0290,
		IME_KEYUP = 0x0291,
		NCMOUSELEAVE = 0x02A2,
		DWMCOMPOSITIONCHANGED = 0x031E,
		DWMNCRENDERINGCHANGED = 0x031F,
		DWMCOLORIZATIONCOLORCHANGED = 0x0320,
		DWMWINDOWMAXIMIZEDCHANGE = 0x0321,
		DWMSENDICONICTHUMBNAIL = 0x0323,
		DWMSENDICONICLIVEPREVIEWBITMAP = 0x0326,
		USER = 0x0400,
		TRAYMOUSEMESSAGE = 0x800,
		APP = 0x8000,
	}
}